Barbro,

Luckily, most Royal Navy records survive.

There are two different ways you can go:

1. Try to trace your grandfather, via his service record. I would recommend you do this first, as it’s easier and will tell you whether you need to get ahold of H 31's logs etc.

Start here: [www.nationalarchives.gov.uk]

2. Try to trace H 31, likely via her logs. If these exist, they would be at The National Archives, Kew but not online.

Best wishes,
Michael